Crosslinkable polymeric coatings and films and composite structures incorporating same

Abstract

A film having a width of at least about one foot as defined by the cross machine direction thereof and a substantially uniform average thickness of less than about 10 mils is formed of a crosslinkable thermoplastic olefin polymer, a crosslinking agent, and preferably a flame retardant. The film can be combined with a suitable substrate to form a prepreg or coated substrate, and the prepreg or coated substrate can be subsequently treated under conditions to crosslink the olefin polymer and to form a rigid composite structure. The composite structure is particularly useful for printed circuit board applications.

That which is claimed is: 
     
       1. A multilayered composite structure comprising a plurality of adjacent layers, wherein at least one of said adjacent layers comprises a sheet comprising a substrate and a cast film coated onto a surface of said substrate, said cast film having a width of at least about one foot as defined by the cross machine direction of said cast film, said cast film comprising a crosslinkable thermoplastic olefin polymer and a crosslinking agent capable of reacting with and effecting crosslinking of said olefin polymer, said cast film having a substantially uniform average thickness of less than about 10 mils across a substantial portion of the width thereof. 
     
     
       2. The multilayered composite laminate structure according to claim 1, wherein said laminate further comprises a flame retardant agent. 
     
     
       3. The multilayered composite laminate structure according to claim 1 wherein said composite structure has been treated under conditions sufficient to effect crosslinking of said polymer to form a substantially rigid unitary multi-layered composite structure. 
     
     
       4. A printed circuit board comprising a laminate according to claim 1. 
     
     
       5. A multilayered composite structure comprising a plurality of adjacent layers, wherein at least one of said adjacent layers comprises a sheet comprising a substrate and a film coated onto a surface of said substrate, said film having a width of at least about one foot as defined by the cross machine direction of said film, said film comprising a crosslinkable thermoplastic olefin polymer and a crosslinking agent capable of reacting with and effecting crosslinking of said olefin polymer, said film having a substantially uniform average thickness of less than about 10 mils across a substantial portion of the width thereof, wherein said film is a cast film produced by extruding a molten composition comprising a crosslinkable thermoplastic olefin polymer and a crosslinking agent capable of reacting with and effecting crosslinking of said olefin polymer, to produce a substantially molten polymer extrudate having a width of at least about one foot as defined by the cross machine direction of said extrudate; and drawing said molten extrudate at a draw down ratio of at least about 3:1 to form a film having a substantially uniform average thickness of less than about 10 mils; and   wherein said film is directed into a face-to-face opposing relationship with said substrate; and a substantially uniform pressure is applied across the width of said film and said substrate by directing said film and substrate through the nip formed by cooperating metal casting roll and pressure roll having an elastomeric surface, wherein said pressure roll is in direct contact with said molten film to provide a substantially uniform film thickness of less than about 10 mils across a substantial portion of the width thereof.   
     
     
       6. A multilayered composite structure comprising a plurality of adjacent layers, wherein at least one of said adjacent layers comprises a sheet comprising a substrate and a cast film coated onto a surface of said substrate, said film having a width of at least about one foot as defined by the cross machine direction of said film, said film comprising a crosslinkable thermoplastic olefin polymer and a crosslinking agent capable of reacting with and effecting crosslinking of said olefin polymer, said film having a substantially uniform average thickness of less than about 5 mils across a substantial portion of the width thereof.